In the past, capped wheel nut assemblies have been made by welding the cap on the nut. Usually the nut is made of steel with a zinc plate and the cap is stainless steel. A welded joint between the nut and the cap is a corrosive site because of the different metals involved. These corrosive sites lead to weakening or failure of the bond. Elimination of the welded joint eliminates these corrosive sites. Elimination of the welded joint also prevents formation of stress risers in the cap.
As an alternative to a welded joint, an adhesive bond has been employed, of the type disclosed in U.S. Pat. No. 4,764,070. The adhesive bond insulates the two metals from each other and resists corrosion. The adhesive, however, must be capable of retaining its adhesive character over a very wide range of temperatures and also must not break down or allow moisture to enter between the nut and the cap. Moisture leads to corrosion and possible failure.